Laws do not persuade just because they threaten.

Seneca’s point is that coercion can secure outward compliance but rarely produces inward assent. A law that relies chiefly on fear of punishment may deter some actions, yet it does not “persuade” in the deeper sense of forming conviction or moral understanding. In Stoic terms, genuine ethical behavior comes from reasoned judgment and the cultivation of virtue, not from external compulsion. The remark also implies a political lesson: stable civic order depends on citizens who grasp and endorse the justice of rules, not merely subjects who obey under threat. Threats may restrain, but they do not educate the will.